1. Field of the Invention
The present invention relates to adjustable wrenches used to manipulate fasteners such as nuts and bolts. Specifically, the present invention relates to an adjustable wrench having a fastener-receiving region into which shims are rotated to incrementally adjust the dimensions of the opening to accommodate a wide range of fastener sizes in two different measurement systems such as inch and metric units.
2. Description of the Prior Art
There are many times when people want to have a few basic hand tools with them so they can perform minor tasks quickly and conveniently. Common activities such as biking, camping, and fishing often require a person to make a simple repair or adjustment. Carrying a complete, multi-piece tool set with you at all times is not a practical option. Adjustable or multifunction tools are often the perfect compromise between utility, size and weight. For maximum utility, an adjustable wrench must be able to accommodate a wide range of fastener sizes and ideally be able to accommodate both inch and metric units.
Two types of wrenches have been proposed in the prior art in an attempt to meet this need: infinitely adjustable and incrementally adjustable.
A common example of an infinitely adjustable wrench is the Crescent.RTM. wrench, manufactured by Cooper Tools, 3535 Glenwood Ave., Raleigh, N.C. 27622. This design utilizes a fixed jaw and a movable jaw with teeth that engage a worm gear. Rotating the worm gear moves the movable jaw, allowing infinite adjustment in size. While this wrench has achieved widespread commercial acceptance, it has serious deficiencies in usage. The primary deficiency is the overall bulk of the head. This bulk is required to adequately support the movable jaw and the worm gear but it limits the use of the wrench in tight spaces. Another deficiency is the need to constantly adjust the wrench during use. This problem is the result of the loose tolerance in the fit of the worm gear to the movable jaw, which is required for the mechanism to work smoothly. To effectively use this tool, the user must place the jaws over the fastener, rotate the worm gear until the jaws are in firm contact, and then apply torque. Tight spaces can make this adjustment process difficult. The looseness also results in the degradation of the fit of the jaws to the fastener each time the wrench is removed from, and then re-applied to, the fastener. Therefore, the worm gear must be manipulated each time the wrench is removed and re-applied.
Efforts to address the aforementioned deficiencies in the crescent-type wrench have resulted in only minor improvement. For example, U.S. Pat. No. 4,753,141 to Hamrick (Jun. 28, 1988) utilizes a biasing spring that acts on the worm gear to press it against the teeth of the movable jaw. While this spring does reduce looseness, it does not eliminate the problem. The user must still periodically re-adjust the wrench during use.
Another example of an infinitely adjustable wrench is the Clench Wrench.TM., marked patent pending, sold by Sears, Roebuck and Co., 3333 Beverly Road, Hoffman Estates, Ill. 60179. This wrench relies on user applied torque on the handle to cause the jaws to grip the fastener with correspondingly increasing pressure. To use this wrench, the user must use a thumb or finger to open the jaws, place the wrench onto the fastener, allow the jaws to contact the fastener, and then reposition the hand onto the handle before torque can be applied. This action requires clearance that is not available in tight quarters. Another deficiency in this design is that the wrench must remain in the same plane as a nut for it to properly grip the flat sides of the nut. If, for example, the handle needs to be angled slightly to clear an obstacle, the jaws can easily slip off the nut. Still another problem with this design is that the grip on the fastener increases as torque is applied. The result is that the flat sides of a nut can be scarred as the jaws of this wrench dig into the material. This scarring not only causes cosmetic damage to the fastener but can also result in raised material on the flats that can interfere with subsequent use of other tools such as conventional wrenches or sockets.
Since nuts and bolts are produced in discrete sizes (such as 9/16, 1/2, 7/16-inch or 14, 13, 12-millimeters), an incremental approach to adjustment can also be used. Wrenches incorporating sliding or rotating shims for incremental adjustment have been proposed. Examples of this type of wrench include: U.S. Pat. No. 4,324,160 to Maclay (Apr. 13, 1982); U.S. Pat. No. 102,336 to Utley (Apr.26, 1870); U.S. Pat. No. 1,080,064 to Huber (Dec. 2, 1913); U.S. Pat. No. 1,399,966 to King (Dec. 13, 1921); U.S. Pat. No. 1,550,564 to Nagano (Aug. 18, 1925); and U.S. Pat. No. 1,646,140 to Dickie (Oct. 18, 1927). These wrenches can accommodate several sizes of fasteners. However, none of these prior art examples can accommodate both inch and metric unit fastener sizes in the same jaw opening. Following the teachings of the prior art, the only way to produce an incrementally adjusting wrench capable of handling both inch and metric unit fastener sizes would be to make it double-ended, with one end configured for inch unit fastener sizes and the other end configured for metric units.
From the above discussion, it can be seen that many efforts have been made in an attempt to produce an adjustable wrench that is:
quickly and easily adjusted to fit a wide range of fastener sizes in both inch and metric units, PA1 a minimum overall size and weight, PA1 capable of maintaining a precise size setting during use, and PA1 simple, strong, and economical to manufacture. PA1 to provide an adjustable wrench that can accommodate a wide range of fastener sizes; PA1 to provide an adjustable wrench that can accommodate both metric and inch-sized fasteners in the same jaw opening; PA1 to provide an adjustable wrench that combines maximum utility with minimum overall size; PA1 to provide an adjustable wrench that once the proper size is selected, will not change in size during use; and PA1 to provide an adjustable wrench that utilizes a simple design to minimize costs of manufacture and assembly.
Nowhere is the need for minimum size and maximum versatility more critical than in the case of the now common multifunction or combination tool. These tools, typified by U.S. Pat. No. 4,744,272 to Leatherman (May 17, 1988), generally take the form of a folding a a folding pair of pliers with several fold out implements such as knife blades, screwdrivers, files, saws, etc. stored in the handles (like the blades in a folding pocketknife). The result is a versatile tool that is convenient and compact. However, the only means provided to tighten a nut are pliers. Pliers, while useful, are not particularly well suited for this task since the user's grip strength determines the amount of torque that may be applied and they often cause damage to the fastener. Prior art adjustable wrenches have not been incorporated in these multifunction tools as fold out implements because of their bulk.
U.S. Pat. No. 5,920,935 to Beck (Jul. 13, 1999) shows a combination tool that incorporates an adjustable crescent-type wrench. However, since this wrench is an integral part of the handle and not a fold out implement, the overall size of the tool is increased, reducing its portability.
U.S. Pat, No. 5,062,173 to Collins (Nov. 5, 1991) shows a multifunction tool that incorporates a three-size, non-adjustable wrench as a fold out implement. This design, while maintaining the compactness desired in these combination tools, offers very limited functionality.
Clearly, there remains a need for a versatile, highly functional, adjustable wrench that is small enough to be incorporated as a foldout implement in a common multifunction tool.